15655561 has 4 divisors (see below), whose sum is σ = 15799300. Its totient is φ = 15511824.

The previous prime is 15655553. The next prime is 15655603. The reversal of 15655561 is 16555651.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16555651 = 7 ⋅2365093.

It can be written as a sum of positive squares in 2 ways, for example, as 11182336 + 4473225 = 3344^2 + 2115^2 .

It is a cyclic number.

It is not a de Polignac number, because 15655561 - 2³ = 15655553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (15655501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 71706 + ... + 71923.

It is an arithmetic number, because the mean of its divisors is an integer number (3949825).

Almost surely, 2^15655561 is an apocalyptic number.

It is an amenable number.

15655561 is a deficient number, since it is larger than the sum of its proper divisors (143739).

15655561 is a wasteful number, since it uses less digits than its factorization.

15655561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 143738.

The product of its digits is 22500, while the sum is 34.

The square root of 15655561 is about 3956.7108815277. The cubic root of 15655561 is about 250.1628858498.

The spelling of 15655561 in words is "fifteen million, six hundred fifty-five thousand, five hundred sixty-one".